They hypothesized that TRAIL works synergistically in combination with a compound named procaspase activating compound 1 (PAC-1), a caspase 3 activating agent, to increase tumor cell apoptosis, and their results support the synergistic action of PAC-1 and TRAIL in GCT.23,24 PAC-1 is already being investigated as a potential anti-cancer therapy in gliomas in rodents, canines, and humans25–27 as well as osteosarcoma and lymphoma.28 To circumvent TRAIL’s short half-life,29 Crosley et al. proposed a recombinant oncolytic vaccinia virus (OV) that promotes TRAIL production. The gene discussed is TNFSF10; the disease is osteosarcoma.